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BMS JB4 'Piggyback' Tune for the 2.4T Outback(s)

29007 Views 515 Replies 36 Participants Last post by  teamdrop
After searching for available performance parts for the 2.4T, I learned that Burger Motorsports had the JB4 available for the ‘22+ WRX. I reached out and they replied that it would work with the 2.4T Outback as well. It is still in Beta format but I still went for it and placed my order. I received it on Monday and spent 1hr last night installing it. I opted for the Bluetooth module and purchased the app (personally, I think that they should include a one-time use code if you opt for the BT module add-on because it feels like they’re nickel & diming the customer to keep purchasing extras).
The install was straight forward and the online PDF/directions were pretty thorough (if you have some sort of mechanical competency). Identifying the plugs that are sandwiched was pretty easy. Pulling the HPFP plug was a pain and removing the front belly pan was the most labor intensive to get at the EWG plug at the Turbo. I rigged the OBDll plug and went out the door jamb because I couldn’t access firewall port last night (I will reroute it this weekend when I have time to pull more stuff apart..). After everything was installed and zip tied, I started it and connected the BT app and took it for a drive.
Now, on to the good stuff, and it is good. The JB4 is pretty simple in function; uses general operating parameters with data collected from motor via the module plugs & OBDll plug to override the factory mapping and controls the Electronic Waste Gate to hold boost longer rather than bleeding it (simplest explanation without getting too technical). I certainly feel the added power without a doubt. The drivability is absolutely normal and feels like stock in terms of the cars mannerisms while driving. The power comes on smooth and pulls harder all the way to redline. The CVT is totally unaffected by the additional power and drives and ‘shifts’ very similar to normal. In the end, it really is about a 40-50hp gain and is very suitable for the Outback considering the weight of the car, gearing and the fact that it IS NOT a WRX. I have only run Map2 which is for 93oct. I have ample access to E85 so I could run the E30/40 map too if I wanted and probably will just to test it out. My goal was to add a bit more power, which to me adds some confidence passing, entering a highway etc and for me, goal met. I have driven a true tuned cars for the past 15yrs (with the exception of my Gen5 3.6R) so I do feel that I have a very realistic expectation and understanding of tunes. In this case, I am onboard with the plug & play module vs a remapped ECU tune so that I can remove if/when needed and there’s also going to be a market to sell it down the road to the anyone driving the 2.4T if I decide I do not want it any longer. This option gives me what I think the car needs and I have zero concerns for the CVT handling the power, especially considering others will tow thousands of pounds regularly which will have much more strain on the CVT than adding 40ish more hp. On another note, it is still hot & humid here in the Tri-state area and the car will perform much better when the IAT’s drop with the change of the weather.
I will add some install pics this weekend when I have more time and continue to report progress with more usage. Feel free to ask questions and I will answer as best as I can. I also have ZERO affiliation with BMS and am just sharing information with the community for those that may be interested .

Cheers

Link to product page:
JB4 Tuner for 2022+ Subaru WRX BETA
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My $0.02....

If an aftermarket product, which has the effect of changing the AFR (typically by allowing more air), a product which can monitor and report on AFR should be a requirement. Why?

I am under the impression, which may be incorrect, ECUs are limited in how much they can adjust AFR/timing in response to more air, e.g., removing the charcoal canister. More air with no more fuel results in a leaner mixture.

Perhaps someone who knows the Gen 6 Subaru engines and their ECUs can comment?
I don't KNOW about Gen 6 and their ECU's but here's some speculation - someone correct me if this is off base.

We're not worried about closed loop operation because the oxygen sensor will monitor the situation and the ECU will compensate. It's the open loop operation that's critical. That's where the oxygen sensor is not in the loop, and the engine relies on various other sensors, e.g. throttle position, RPM, MAF (air grams per second) - calculated load, IAT, MAP/Boost, to choose fuel injector and ignition timing values in a map, which still have some dynamic learning involved but it's based on knock correction.

One of the most important sensors in open loop is the MAF - for example if you increase the diameter of the housing that the MAF sensor is in, it will dramatically change the calculation - the MAF calculates air flow past a hot wire and senses how much air is flowing based on how the air cools the sensor wire. If you increase the cross section that the air is flowing through, it moves slower and cools off the wire less, and if you decrease the cross section air will flow faster and cool off the wire more. The MAF is carefully calibrated based on air flow.

But because it's a hot wire sensor, what happens if you cool the charge air before it reaches the MAF? Well cooler air is automatically denser, and we have intake air temperature (IAT) sensors somewhere, and that is used as part of that calculation for air flow, so it should be fine.

I think the ability of the system to compensate for more restriction or less restriction is broad enough that as long as you don't change the way the IAT sensor and MAF sensor operate, it should be fine. The engine will probably run fine if there were no air filter at all, and with a somewhat clogged air filter - at a minimum the useful service life of a paper air filter under semi-dusty conditions.
 

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I'm curious if that rubber padding on the OEM plastic charge pipe is there for sound deadening? I wonder if it can be removed? Since you took your OE charge pipe out, maybe you can investigate, @User1029

The other use for that padding could be to keep the heat within the charge pipe, but I'm not sure I can see the benefit of that. People wrap headers to keep heat inside the exhaust prior to entering the turbo, but we generally want the hot compressed air leaving the turbo to cool down, which is why we have an intercooler.
https://www.reddit.com/r/2022wrx/comments/10e09o2
less joints and less insulation and therefore keeps the charge pipe hot are the improvements of the Perrin over OEM :)

the length of the charge pipe on the FA24DIT engines is quite a bit shorter than the FA20DITA motors. Glad the engineers improved on getting quicker spool :)
 

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https://www.reddit.com/r/2022wrx/comments/10e09o2
less joints and less insulation and therefore keeps the charge pipe hot are the improvements of the Perrin over OEM :)

the length of the charge pipe on the FA24DIT engines is quite a bit shorter than the FA20DITA motors. Glad the engineers improved on getting quicker spool :)
I don't quite follow what you were saying here. How is keeping the charge pipe hot a good thing?

Also I suspect (but could be wrong) that the insulation on the OEM charge pipe is to keep the underhood temperatures from further heating the charged air in addition to maybe providing some sound dampening. I think it's unlikely the charged air is warmer than the ambient temperature under the hood but again I could be wrong about that.
 

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There's a calculator to show the temperature effect of a turbocharger:


So I put in 80 degrees ambient, 15 psi boost, and 100% efficiency and got 197.53F outlet temperature. Safe to say that the turbo is not 100% efficient so if it were putting out actual 15 PSI the temperature would be above 200F.

But in normal driving our cars aren't at full boost, so it's not as if it's always 200F in there. In a car without a turbocharger, a plastic pipe from the air filter to the throttle body keeps the intake air cooler than a metal tube would, but in a turbocharged car, the situation can go either way, depending on whether you're on boost or not. At boost I'm pretty sure the charge air is warmer than the engine bay temp. The intercooler itself should also be cooler than engine bay temp if the car is moving and there's that ambient air being funneled through it, but when the car isn't moving, our top mount intercoolers will get warm.

There's a company that make charge pipes with heatsink fins to pre-cool the air before it reaches the intercooler - no idea how effective it is.

 

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There's a calculator to show the temperature effect of a turbocharger:


So I put in 80 degrees ambient, 15 psi boost, and 100% efficiency and got 197.53F outlet temperature. Safe to say that the turbo is not 100% efficient so if it were putting out actual 15 PSI the temperature would be above 200F.

But in normal driving our cars aren't at full boost, so it's not as if it's always 200F in there. In a car without a turbocharger, a plastic pipe from the air filter to the throttle body keeps the intake air cooler than a metal tube would, but in a turbocharged car, the situation can go either way, depending on whether you're on boost or not. At boost I'm pretty sure the charge air is warmer than the engine bay temp. The intercooler itself should also be cooler than engine bay temp if the car is moving and there's that ambient air being funneled through it, but when the car isn't moving, our top mount intercoolers will get warm.

There's a company that make charge pipes with heatsink fins to pre-cool the air before it reaches the intercooler - no idea how effective it is.

Can you type up a flow diagram where this thing would integrate with the perrin charge tube?
 

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If the blue lines are the stock intake and charge pipe, and the red lines are the aftermarket, the aftermarket stuff is somewhat erratic even though it has higher peak. Did the ECU cut power at 4000 RPM (peak torque as you mentioned) to cause that? Do you get the power cut on the road or only on the dyno?
 

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I’ve downgraded to map3 just to limit the extra torque and avoid the wall. At least I hear a ton of turbo noises lollll

The intake and charge pipe did provide some solid gains of 20-30wtq before the torque cut off
Are you able to monitor A/F ratio after installing the charge pipe to see if it had any negative impact? I wouldn't expect any but it would be nice to confirm whether or not that sucker requires any level of tunage.
 

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installed the 2022 WRX Perrin charge pipe today :)

1. Fitment is perfect for the outback XT
2. The instructions said to take off radiator fan but the Outback radiator fan configuration is different than the WRX. You can’t just take off one fan, you have to off the whole row. I decided not to take off the radiator fans and install still went smoothly.
3. Turbo sounds 15% louder with more streamlined flow and no bottlenecks in the charge pipe :) butt dyno approved :)
Do I really need to take of the Intercooler for install?
 
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